A radio communication system, such as existing two dimensional cellular communication systems, comprise a plurality of cells arranged to reduce interference and improve frequency reuse primarily in two dimensions (i.e., one horizontal plane). However, current two dimensional cellular systems have failed to satisfy the communicational needs within multi-level structures. Within multi-level structures, users produce a very high localized density demand that quickly exhaust the capacity of the current cellular systems. The problem is further compounded, because in two dimensional systems the radii of cells are much larger than the sizes of the multi-level structures and more than one multi-level structures may be contained within a single cell radius.
Additionally, the capacities of existing cellular communication systems are quickly exceeded because these systems do not discriminate between users on different levels of multi-level structures. That is, these cellular systems assign channels of the same frequencies to all the users in a localized area, irrespective of what level of the structure a particular user may be on. Thus, the high demand indicative of multi-level structures (e.g., busy office building, hospital, banks, and hotels etc.) quickly frustrates the current two dimensional cellular systems, rendering them ineffective in these multi-level environments because too many out going calls are blocked.
In multi-level structures, the users of the conventional wire line telephone systems consistently miss calls if their jobs require a high degree of mobility. Secretaries frequently experience difficulty in locating their supervisors and co-workers because they are never where they were supposed to be. Individuals that miss important calls may choose to carry pagers, but pagers do not satisfy the need for full-duplex (i.e., two-way) mobile communication. Therefore, an effective alternate communication system is needed for the conventional wire line desk telephone that provides full-duplex communication. This system, while satisfying the mobility of users as the existing two dimensional cellular systems, should resolve the problems associated with localized density and high frequency demands that are placed upon these system by users within multi-level structures.
Thus, what is needed is a three dimensional cellular system to satisfy the much needed communication service for this highly localized density of people (e.q., within multi-level structure) whose movements are not restricted in two dimensions, but are consistently characterized by vertical and horizontal directions (i.e., three dimensional).